This invention pertains to a method and apparatus for inspecting empty bottles for foreign bodies, dirt spots and other contaminants.
In one known bottle inspecting apparatus, the bottles are transported along a circular path on rotating support plates which pass the bottles through an inspection zone. A gripping element grips the bottle to be inspected between the head and mouth and maintains the grip at the one place from entry to exit of the inspection zone. The bottles are also stabilized by a downwardly moving socket during passage through the inspection zone. The bottles are scanned with optoelectronics devices in an inspection zone. As a result of accurate and stable fixation of the bottles due to grasping, this known apparatus permits high transport capacities and a high degree of inspection accuracy. It is, however, disadvantageous that the uppermost region of the bottles, that is, the part of the head of the bottle immediately below the upper grasping point is not accessed well as a result of the gripping device shadowing at least a small zone on the bottle. Because users now demand that the entire lateral wall from the bottom to the mouth of a bottle be inspected thoroughly, apparatus of this kind can no longer be used. An example of such apparatus is shown in U.S. Pat. No. 3,411,009.
Another German Patent DE-AS No. 22 62 556 discloses a method for inspecting filled ampules for contamination. According to this prior method, the ampules are again grasped only once during the entire inspection process between the bottom and the shoulder and they are then moved through the inspection area along a circular path while they are being rotated by means of rotating the disks on which they are supported. This apparatus also permits high speed inspection as a result of grasping the ampules axially. Inspection, however, is limited to the relatively short vertical region of the ampules between the two grasping points while the total neck and head region which is concealed by a tube-like grasping element is not checked. This method is, therefore, also not acceptable for total lateral wall inspection.
According to another known apparatus, the bottles are pressed by fingers against rotating friction rollers which contact the wall of the bottle as it is transported through the inspection zone along a circular path. This device is disclosed in German Patent DE-AS No. 1,648,640. In this device there is no support for grasping the bottles in an axial direction. The device is suitable for inspecting the entire side wall of a bottle but it has been shown that supporting the bottles by means of lateral friction forces alone permits neither high output nor reliable testing because of deviations in form and dimensions within a category of bottles as is typical for beverage bottles.
In another known method for testing filled ampules for contamination, the ampules are grasped only in the bottom region by turntables which are equipped with a suction orifice. This device is described in German Patent DE-AS No. 1,573,687. The turntables do not have any transport function. Holding the ampules by means of vacuum after their bottom surface is practical only for relatively small and light ampules but it is not practical for large and heavy beverage bottles. With this device fixation of bottles would not be reliable enough to permit high transport speed at high quantity output of the bottles because of the tenuous grip on the bottles which vacuum provides. Irregularities in the bottom area of the bottles further weakens the vacuum grip.
Another method for detecting contaminants in empty beverage bottles is described in German Patent DE-AS No. 22 40 833. With this method the bottles are carried on a supporting surface interfaced only with their bottoms and they are moved through the inspection zone with no additional support. Checking the entire lateral wall of the bottles is easily achieved. But the stability of the free standing bottles is minimal and is not suited for high output of inspected bottles.